The association of metal ions with nucleobases is being studied, using ions which form substitution inert complexes. This work has a dual goal: to observe the effect of the metal ions on the properties of the coordinated nucleobases, and to improve specificity in the association with various nucleobases. In current work, the association under equilibrium control for ruthenium ammines is being studied, and the groundwork is being laid for the attachment of complexes of the heavier congener, osmium. The study of the influence on the reactivity of ligands on being coordinated to ruthenium(II) and ruthenium(III) ammines is underway. In one project, the possibility of making C-C bonds using CO or CO2 as the source of extra carbon is being investigated; in another, the reactivity of sulfur ligands with special concern for reactions involving S-C bond cleavage. BIBLIOGRAPHIC REFERENCES: Rutheniumammine Complexes of Hydrogen Sulfide and Related Ligands, C.G. Kuehn and H. Taube, scheduled for February, 1976, J. Amer. Chem. Soc. The Reduction of Pyrazine Oxide and of its Complex with Ruthenium(II), M. Blesa and H. Taube, Inorg. Chem., 1976.